This report presents the proposed processing design for a 4,500 tpd crushing and ore sorting circuit feeding a 3,940 tpd grinding and sequential flotation plant to produce copper and zinc concentrates from volcanogenic massive sulphide mineralization.
Report context
This technical report, dated 2021, documents the feasibility study for the Kutcho Copper Project. The recovery methods section describes the proposed process facilities based on metallurgical test work results, historical reports, and engineering design. The report distinguishes between proposed design criteria, historical data used as reference, and test work results that informed the flowsheet development.
Processing route
Crushing and ore sorting
The proposed crushing plant will process ore at 4,500 tpd using a jaw crusher in open circuit followed by secondary crushing with a cone crusher and double deck screens. Two Tomra XRT particle ore sorters will process the -75 mm +25 mm and -25 mm +12.5 mm size fractions, with material finer than 12.5 mm bypassing the ore sorter. The ore sorters are estimated to reject 15% of the sorter feed as waste based on test work. The crushing circuit will operate at 70% availability.
Grinding circuit
The proposed two-stage grinding circuit will comprise a SAG mill in open circuit producing a transfer size T80 of approximately 600 µm, followed by a ball mill in closed circuit with cyclones targeting a final product P80 of 55 µm. Grinding and flotation circuits will operate at 92% availability, 24 hours per day, 365 days per year.
Flotation circuits
A sequential flotation process is proposed, starting with copper rougher and cleaner flotation including a regrind circuit targeting P80 of 15 µm, followed by zinc rougher and cleaner flotation with three stages of cleaning and a regrind circuit targeting P80 of 20 µm. Reagent additions include zinc sulphate for sphalerite depression, sulphur dioxide and sodium sulphide in copper flotation, and copper sulphate for sphalerite activation in zinc flotation.
Concentrate dewatering and tailings
Copper and zinc concentrates will be thickened in 11 m diameter high-rate thickeners and dewatered using pressure filters to 8-9% moisture. Final tailings will be thickened in a 25 m diameter thickener to 65% solids and pumped to the tailings management facility. Water will be reclaimed from the TMF and treated for re-use.
Key reported parameters
| Description | Unit | Value | Source |
|---|---|---|---|
| Crushing plant feed rate | tpd | 4,500 | Design |
| Ore sorter waste rejection | % of sorter feed | 15 | Test work |
| Process plant feed rate after ore sorting | tpd | 3,940 | Design |
| Grinding product size P80 | µm | 55 | Design |
| SAG mill power | kW | 2,000 | Design |
| Ball mill power | kW | 3,250 | Design |
| Copper rougher flotation time | min | 30 | Test work |
| Copper regrind product P80 | µm | 15 | Test work |
| Zinc rougher flotation time | min | 18 | Test work |
| Zinc regrind product P80 | µm | 20 | Test work |
| Copper concentrate grade | % Cu | 25.5 | Mine plan |
| Zinc concentrate grade | % Zn | 55.1 | Mine plan |
| Copper recovery to copper concentrate | % | 87.2 | Mine plan |
| Zinc recovery to zinc concentrate | % | 71.5 | Mine plan |
| Copper concentrate production | tpd | 239.2 | Design |
| Zinc concentrate production | tpd | 136.3 | Design |
| Bond ball mill work index (average) | kWh/t | 14.1 | Test work |
| SAG mill steel wear rate | kg/t | 0.28 | Test work |
| Ball mill steel wear rate | kg/t | 0.80 | Test work |
| Crusher availability | % | 70 | Design |
| Grinding and flotation availability | % | 92 | Design |
Project website: https://kutcho.ca/kutcho-project/
Technical qualifications
The report notes that partially oxidized floatable ore comprises about 2.6% of total feed tonnage, with limited test work completed on this material. The qualified person determined that recovery for oxide material should be reduced by 10% compared to sulphide ore and mass pull increased by 25%. Reagent consumption estimates from test work were modified to show a 25% reduction based on expected operational experience. Ore sorter grade and recovery estimates were based on a bulk ore sorting sample from drillhole core. Penalty grades other than zinc in copper concentrate were taken from assays of locked cycle final cleaner product from 2021 metallurgical test work.
Source: Kutcho Copper Project , 2021 Technical Report, Section 17 Recovery Methods, CSA Global Report № R533.2021
